How to determine USB hub speed type?

Question

I'm developing a driver for multiple USB speeds and according to the universal specification, I'm allowed to draw a greater amount of current from a USB 3.0 hub than the other versions.

Is there a way on Windows to determine the different USB speeds? I'm basically asking for a place to get started. Thanks in advance.

Answer 1

Since you're using Windows, you should look into using Windows Driver Frameworks (WDF). This is the Windows equivalent to libusb on POSIX-compliant computers.

WDF Reference

Look through the example code (there's a toaster/firefly driver example in there) on how to set up a WDFIOTARGET given a device ID. Use this implementation with your hub, enumerating it upon device insertion.

Then, you'll want to send the IOCTL, IOCTL_USB_GET_NODE_INFORMATION, to the hub represented by a WDFIOTARGET in order to retrieve a USB_NODE_INFORMATION structure.

                                      

IOCTL Reference

USB_NODE_INFORMATION Reference

Then, retrieve with the following access pattern:

PUSB_NODE_INFORMATION UsbNodeInfo = NULL;
// retrieve UsbNodeInfo here with your USB_GET_NODE_INFORMATION signal
UCHAR DescriptorType;
DescriptorType = UsbNodeInfo->u.HubInformation.HubDescriptor.bDescriptorType

HubInformation Reference

HubDescriptor Reference

This will retrieve a descriptor type of either 0x2A (3.0) or 0x29 (2.0 or lower). Using this information, you can send the proper IOCTL you want to the device in order to demand a greater amount of current from the hub like so:

if (DescriptorType == 0x2A) {
    // handle USB 3.0 current specification here
} else {
    // handle USB 2.0 current specification here
}

Hopefully this is enough for you to get started. Enjoy!